This application claims the priority of German Patent Document 100 43 631.5, the disclosure of which is expressly incorporated by reference.
The present invention relates to a linear operating device that includes a medium for converting a rotational motion into a translational motion, which is realized as a nut, a rotating drive unit and a spindle, which acts in conjunction with the nut; and the nut is connected with the spindle in such a manner that it maintains its ability to rotate.
A linear operating device of this type is known from European Patent Document EP 0 603 067. This linear operating device is envisioned particularly for use on spacecraft. In this instance the nut is realized as a thread rolling mechanism. The spindle is connected with torsional strength to a rotating drive unit.
As an alternative to the thread rolling mechanism referred to above, a ball nut is known from German Patent Document DE 42 08 126 and corresponding U.S. Pat. No. 5,263,381, which also acts in conjunction with a spindle to convert a rotational motion into a translational motion.
In the context of the present state of the art in accordance with European Patent Document EP 0 603 067, the spindle of the linear drive is always connected to the rotating drive unit. Elements that are connected with the nut can be moved in a translational way in relation to the spindle, or, in the extreme consequence, they can even be detached from the spindle. However, this is accompanied by the risk that with larger elements that are to be moved in a translational manner or with elements that are to be connected temporarily with the spindle it will be necessary to use a spindle that is correspondingly large and that will, after release of the connection between the nut and the spindle, remain as a relatively large and disturbing element on the rotating drive unit and possible other components that are attached to the rotating drive unit. With regard to the example of the unfolding of a solar generator on a spaceship, this would mean that after the solar generator has been unfolded a relatively long spindle would stick out from the surface of the spaceship that could obstruct the movement of the solar generator, or even cause damage to the solar generator.
Specifically, with respect to the case of an unfolding system for solar generators, different construction types are known from German Patent Document DE 196 49 739 and corresponding U.S. Pat. No. 6,073,914, but they are associated with certain disadvantages. A pyrotechnical release entails the problem that a relatively high shock acts upon the solar generator unit and/or on the structures carrying it, which would, in spacecraft applications, cause considerable disturbances. In addition, there exists a risk of particles flying about that can result in damage to the solar generator apparatus or other mechanisms. German Patent Document DE 196 49 739 also discloses non-pyrotechnical release devices. However, these devices are also associated with the risk of particles flying about or with the risk, as in the embodiment claimed in German Patent Document DE 196 49 739, of a jam-up. Consequently, a failure to release cannot be precluded.
It is therefore an object of the present invention to provide a linear operating device that will remedy the disadvantages of the state of the art referred to above and that allows, particularly in the context of the application in space travel, operation without shock effect or particles flying about.
The objective is achieved with the rotating drive unit being rotatably fixed to the nut or the rotating drive unit exercising a force in an axial direction of the spindle on an area of the spindle that acts in conjunction with the nut. Other certain preferred embodiments of the present invention include a spacecraft and a solar generator unfolding system featuring a linear operating device.
The linear operating device preferentially includes a rotating drive unit rotatably fixed to the nut. Consequently, by way of a rotational motion of the nut, which is caused by the rotating drive unit, it is possible to generate a translational motion of the spindle, which, in the ultimate consequence, will result in the detachment of the spindle from the nut. This way, the spindle, that may be very long, no longer stays on the rotating drive unit and the components attached to it. The rotating drive unit can be realized, for example, as a motor or as a spring.
In further certain preferred embodiments, it is also possible to envision as an alternative or in conjunction with the preferred embodiments referred to above that one (or, if need be, another or even several) rotating drive unit(s) exercise(s) a force in the axial direction of the spindle in that area of the spindle that acts in conjunction with the nut. Thus, it is possible to cause the nut to rotate, solely by or supported by the effect of this tensile load or pressure load, which effects in turn a translational movement of the spindle. In this case, the rotating drive unit can be realized as an elastic element.
In particular in certain preferred embodiments, it can be envisioned that the spindle is realized as pre-stressed and extensible. To be considered in this context are all kinds of suitable materials and construction types for the spindle, which, obviously, must be adjusted to the respective pre-stress. The spindle can be manufactured, for example, from titanium or steel in order to absorb high pre-stresses, and it can be manufactured as a solid element or as individual elements, such as fibers or rods, in order to provide a correspondingly lower or higher level of elasticity. Other suitable materials, for example non-metallic materials, or other construction types are also possible.
On the other hand, in certain preferred embodiments, it is also possible to envision, in the alternative or in addition, that at least one elastic element, for example a spring element, is envisioned as rotating drive unit, which exercises a pre-stress, i.e. a tensile load or a pressure load, on the spindle. Thus, analogous to the previous description, this elastic element is then able to cause the nut to rotate by way of applying the tensile load or pressure load upon the spindle.
In certain preferred embodiments, the nut has an operative connection with the spindle via rolling bodies. This ensures that during the rotational motion of the nut, with regard to the spindle, only the rolling resistance must be overcome, but no sliding resistance occurs between the nut and the spindle. Envisioned as suitable rolling bodies can be, for example, rollers or balls that are known from the state of the art referred to previously.
In certain preferred embodiments, in order to stop the nut before it executes the rotational motion, it is possible to envision a lock device, where the nut is attached to a first lock device rotatably fixed. This lock device can be part of the nut itself, but it is also possible to envision another element to which the nut is suitably attached with torsional strength. The first lock device is realized in such a way that it can be connected, detachably and rotatably fixed, to a complementary lock device. This way it can be guaranteed that, provided both lock devices are in a stop position, they are arresting any rotational motion of the nut, and after the lock devices are released from each other the nut is able to execute the desired rotational motion. To accomplish this, the first lock device can be equipped with a projection or a recess on its surface, while the complementary lock device features a form that is complementary to the projection or the recess. The only requirement for this complementary form is that it is realized appropriately in such a way that it can act effectively in conjunction with the projection or the recess in order to block any undesired rotating of the nut.
To ensure tension-free operation of the linear operating device, it can be envisioned that the spindle and the nut are arranged in mountings with the ability to tilt. This way it is possible to make adjustments for any mutual displacement of the mountings of spindle and nut. Consequently, the mountings are realized in a suitable form, preferentially as ball-and-socket joint or in another appropriate way.
This linear operating device can be used in all instances where items must be connected in such a way that they are displaceable in relation to each other, and particularly where items are to be detachably connected with each other and are to be released subsequently, e.g. released within the meaning of opening, extending, folding out or separating. Thus, this is a device that provides a solid connection in its reeled-in condition which can then be easily released, particularly by also applying remote activation.
In other certain preferred embodiments of the present invention, a spacecraft is equipped with the linear operating device described previously. The rotating drive unit can, for example, be connected to the spacecraft, and the spindle can be connected to detachable, extendable or unfoldable mechanisms of the spacecraft. Devices of this type can be, for example, solar generator units or antenna devices of the spacecraft, other masts, landing legs, loads that are to be put out, several spacecrafts (for example, satellite piles) or even a parent or secondary spacecraft that is to be separated from the other craft, respectively.
In certain preferred embodiments of the present invention, a solar generator unfolding system is equipped with the linear operating device described above. In this instance, the linear operating device can be envisioned particularly as part of a hold-down and release system for unfolding a solar generator unit.
In certain preferred embodiments, it can be envisioned that the nut is connected to a supporting structure of the solar generator unit and that the spindle is connected to an outermost panel element of the solar generator unit. This way it is possible to ensure that upon unfolding of the solar generator unit the spindle will be removed from the supporting structure, e.g. a solid frame, a vehicle, a spacecraft etc., so that it cannot be the cause of disruptions at that location.
To guarantee tension-free operation it is possible to envision that the spindle is arranged in a first mounting with the ability to tilt vis-à-vis the outermost panel element of the solar generator unit, and the nut is arranged in a second mounting with the ability to tilt vis-à-vis the support structure. Thus, any possible displacement of the solar generator unit vis-à-vis the support structure can be compensated for in a simple manner.
Preferred embodiments of the present invention are subsequently described in more detail using the FIGS. 1 to 6.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.